Regular Polygon Calculator

Number of sides of the regular polygon (minimum 3).
Length of one side of the regular polygon.
Math Updated 16 Jun 2026

Regular Polygon Calculator is a mathematics calculator that helps you calculate regular polygon values from your input data. The formula used is: Area = (n×s²)/(4×tan(π/n)); Inradius = s/(2×tan(π/n)); Circumradius = s/(2×sin(π/n)); Interior angle = (n−2)×180/n. Ensure all inputs share the same unit system (e.g. all metres or all feet) unless the formula converts between units.

Formula

Area = (n×s²)/(4×tan(π/n)); Inradius = s/(2×tan(π/n)); Circumradius = s/(2×sin(π/n)); Interior angle = (n−2)×180/n
  • Regular Polygon Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
  • Formula: Area = (n×s²)/(4×tan(π/n)); Inradius = s/(2×tan(π/n)); Circumradius = s/(2×sin(π/n)); Interior angle = (n−2)×180/n
  • Input definitions: • Number of Sides: the numeric number of sides used in the calculation • Side Length (cm): the numeric side length (cm) used in the calculation
  • Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
  • Ensure all inputs share the same unit system (e.g. all metres or all feet) unless the formula converts between units.
  • Results are mathematically exact given the formula and your inputs. Rounding to decimal places may introduce small display differences.
  • Check that all inputs are in the valid range for the formula. Some operations (e.g. square root, division) require non-negative or non-zero values.
  • Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.

Example Calculation

Inputs
  • Number of Sides: 6
  • Side Length (cm): 5

Suppose you enter: Number of Sides = 6, Side Length (cm) = 5. The calculator applies the formula (Area = (n×s²)/(4×tan(π/n)); Inradius = s/(2×tan(π/n)); Circumradius = s/(2×sin(π/n)); Interior angle = (n−2)×180/n) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

What is the Regular Polygon?
The Regular Polygon Calculator is a mathematics calculator that helps you calculate regular polygon values from your input data. Ensure all inputs share the same unit system (e.g. all metres or all feet) unless the formula converts between units.
When should I use this calculator?
Use this calculator whenever you need a quick, accurate result for regular polygon values from your input data without working through the arithmetic manually.
What units should I enter?
Ensure all inputs share the same unit system (e.g. all metres or all feet) unless the formula converts between units.
How accurate are the results?
Results are mathematically exact given the formula and your inputs. Rounding to decimal places may introduce small display differences.
How do I interpret the result?
Check that all inputs are in the valid range for the formula. Some operations (e.g. square root, division) require non-negative or non-zero values.
How can I verify the calculation manually?
Use the displayed formula and work through the numbers step by step. If your manual result differs slightly, check rounding and unit conversions first.
Can I use this for planning and budgeting?
Yes. Run best-case, expected, and worst-case inputs to compare outcomes and make safer planning decisions.

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